The microstructural studies of suspension plasma sprayed zirconia coatings with the use of high-energy plasma torches

0476027 - ÚFP 2018 RIV CH eng J - Journal Article
Sokołowski, P. - Nylen, P. - Mušálek, Radek - Łatka, L. - Kozerski, S. - Dietrich, D. - Lampke, T. - Pawłowski, L.
The microstructural studies of suspension plasma sprayed zirconia coatings with the use of high-energy plasma torches.
Surface and Coatings Technology. Roč. 318, May (2017), s. 250-261. ISSN 0257-8972.
[International Meeting on Thermal Spraying (RIPT)/7./. Limoges, 09.12.2015-11.12.2015]
R&D Projects: GA ČR GA15-12145S
Institutional support: RVO:61389021
Keywords : Water-stabilized plasma (WSP) * Gas-stabilized plasma (GSP) * Suspension injection * Columnar microstructure * Two-zones microstructure * Electron backscatter diffraction
OECD category: Coating and films
Impact factor: 2.906, year: 2017
http://www.sciencedirect.com/science/article/pii/S0257897217302645

The presented studies are focused on the microstructure characterization of zirconia-based coatings deposited by two types of high-energy plasma torches: (i) Axial III, and, (ii) hybrid version of Water-Stabilized Plasma (WSP) torch. The suspensions were formulated using solid dispersed phase of: (i) zirconia stabilized with 14 wt of Y2O3 and (ii) zirconia stabilized with 24 wt% of CeO2 + 2.5 wt% of Y2O3 and continuous phase of water with ethanol. The spray process parameters were optimized for each plasma set-up individually. The in-flight observations (shadowgraphy) were performed to optimize the injection of the liquid feedstock into the plasma jet. Then the coatings morphology and coating/substrate interface were characterized using conventional light microscopy and scanning electron microscopy (SEM). The results showed that through the change of deposition parameters various coatings microstructures could be obtained, in particular columnar and two-zones structures. The EDS/EDX and XRD studies showed that there was no significant change in chemical/phase composition of zirconia material before and after spraying. Electron backscatter diffraction (EBSD) method allowed to analyze the grain size in the coating microstructure as well as crystallographic orientation of individual grains. The results showed that coatings were characterized by submicrometric microstructure what corresponded to the size of powder particles used to formulate suspension. No texture was observed in the coatings microstructure. The surface topography analysis which was performed by confocal scanning laser microscopy (CSLM) and Shape From Shading (SFS) technique proved the great influence of suspension concentration on the coating structure.
Permanent Link: http://hdl.handle.net/11104/0272606